Frictionless plunger switch having alignable self-holding contacts



July 1, 1958 c. R. PETER 2,841,670

FRICTIONLESS PLUNGER SWITCH HAVING ALIGNABLE v SELF-HOLDING CONTACTS Filed Dec. 23, 1954 2 Sheets-Sheet 1 I Moriww July 1, 1958 c. R. PETER 2,841,670

FRICTIONLESS PLUNGER SWITCH HAVING ALIGNABLE SELF-HOLDING CONTACTS Filed Dec. 23, 1954 2 Sheets-Sheet 2 65' 5a 9- WW United States Patent FRICTIONLESS PLUNGER SWITCH HAVING ALIGNABLE SELF-HOLDING CONTACTS Charles R. Peter, West Allis, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Application December 23, 1954, Serial No. 477,257

11 Claims. (Cl. 200-104) This invention relates to switches. The invention is described herein as embodied in a switch having a plunger reciprocating in a frame to carry a resiliently mounted bridging contact for cooperation with a pair of stationary contacts.

A disadvantage of prior art switches having a bridging contact resiliently mounted on the bridging contact carrier is that the bridging contact may be separated from the stationary contacts by the electromagnetic forces produced by the current flow through the contacts, especially during a period of high current, such as a transient or a short circuit condition. It has been discovered that this disadvantage may be overcome by providing a core mounted on the bridging contact carrier and an armature mounted on the bridging contact, the core and armature encircling the bridging contact to utilize the flux encircling the bridging contact for causing the core to attract the armature and thereby the bridging contact also to prevent the bridging contact from separating from the stationary contacts.

Another disadvantage of prior art switches is that there is usually no convenient provision for aligning the bridging contact with the stationary contacts.' It has been discovered that this disadvantage may be overcome by providing a panel having stationary contacts mounted thereon and an opening therethrough, by constructing the frame, plunger and bridging contacts as a unit structure all movable together on the panel, and by providing a plate and means releasably fastening the plate and the frame through the opening for releasably clamping the frame to the panel for positioning and securing the unit structure on the panel to thereby conveniently align the bridging and stationary contacts.

It is a further object of this invention to provide means responsive to the current flow through the contacts for preventing separation of a bridging contact from a pair of stationary contacts by electromagnetic forces produced by the current flow through the contacts. Still another object of this invention is to provide such a means without interfering with the electromagnetic arc blowout function of magnets associated with the stationary contacts.

It is a still further object of this invention to provide a switch having means for aligning its movable and stationary contacts.

Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a front view of a switch embodying my invention;

Fig. 2 is a sectional view taken through line IIII in Fig. 1, reduced in size and having parts of the switch removed;

Fig. 3 is a view'taken from line IIlIII of Fig. 1, reduced in size and having parts of the switch removed;

Fig. 4 is a sectional view of a stationary contact assembly taken through line IVIV of Fig. 3;

'ice

Fig. 5 is a sectional view, taken through line VV of Fig. 3; and

Fig. 6 is a view taken from line VIVI of Fig. 2.

In the drawings, a panel 9 supports an iron frame 10 and several pairs of stationary contacts 50, 51; 52, 53; 54, 55 and 56, 57. An iron plunger 20 is mounted on the frame for reciprocating relative thereto. The plunger supports carriers 30, 31, 32, 33 which carry bridging contacts 40, 41, 42, 43 into and out of engagement with the stationary contacts.

Each of the stationary contacts is mounted on the panel as shown in Figs. 4 and 5 for stationary contact 50. A bolt 58 passes through a hole in the panel and a flan e portion 59 of the bolt engages the panel in a countersunk recess 60 in the panel. The bolt is secured to the panel by nuts 61, 62 which draw a spring washer 63 and a plain washer 64 against the panel in another countersunk recess 65 on the opposite side of the panel. The stationary contact has a threaded cavity therein for mounting the stationary contact on the threaded portion 66 of the bolt. A cylindrical permanent magnet 67 is inserted in the cavity and a rubber washer 68 lies between the magnet and the bolt. The permanent magnet provides flux which reacts with the flux encircling an are drawn between the stationary contact and the bridging contact to rotate the are on the contact faces and to extinguish the arc in a manner Well known in the electromagnetic arc blowout art.

The iron frame 10 serves as the core for an electromagnet including a coil 11 wound on a spool 12. The frame may be of any suitable shape and is shown here as cylindrical in shape, having an annular wall 13 open at the end thereof away from the panel and closed at the end thereof which engages the panel. The frame has a shoulder portion 8 abutting the surface of the panel and a neck portion 14 extending into an opening 15 through the panel. A center post core portion 16 of the frame extends from the closed end of the frame toward the open end thereof. The center post and annular wall together define an annulus therebetween for receiving coil 11 and spool 12. The center post has a hole 17 therethrough and a frusto-conical recess 18 therein to receive portions of the reciprocating plunger 20. A groove 19 in the inner side of wall 13 receives a snap ring 69 for retaining spool 12 and coil 11 in the frame. A slot in the wall of the frame receives the leads 76 of the coil. As shown in Fig. 1, a bracket 77 and a screw 78 secure the leads 76 to the panel and the leads are connected to terminals 79 on the panel. Slots 71, 72, 73, 74 in the wall of the frame permit movement of the bridging contact carriers 30, 31, 32, 33 with the reciprocating plunger.

The frame is secured to the panel by means of a clamping plate 80 and releasable fastening means such as screws 81, 82, 83. The plate 80 extends overlappingly across opening 15 and abuts the panel on the side opposite the frame. The screws 81, 82, 83 extend through opening 15 in the panel and are threaded into the closed end of the frame to provide means for releasably securing the frame on the panel by releasably clamping the panel between the plate 30 and the shoulder portion 8 of the frame. The neck portion 14 of the frame is rotatably movable in opening 15 on the panel and the frame and the plate move together as a unit. The plate 80 and screws 81, 82, 83 thus provide for selectively positioning the frame on the panel and securing the frame on the panel in the selected position.

The iron plunger 20 has a collar portion 21 at one end thereof for operation in the open end of the frame. An extension 22 of nonmagnetic material at the other end of the plunger projects through hole 17 in the center post 16 for operation therethrough. A frustoconical shaped portion 23 of the plunger and the frustoconical shaped recess 18 in the center post 16 define an air gap which, as is well known in the art, provides the electromagnet with a fiat pull characteristic. A washer 24 of nonmagnetic material, such as a beryllium copper alloy, separates the iron plunger from the iron center post 16 to prevent freezing of the plunger and center post when the plunger moves through its limit of travel in the direction to close the air gap. As shown in Fig. 1, a stop bar 27 extends across the open end of the frame and is secured to the frame by screws 28. The stop bar limits the plungers travel when moving in the direction to increase the length of the air gap. The collar portion of the plunger, as shown in Fig. 2, provides good flux transmission to the wall 13 of the frame and also provides a convenient structure on which to mount the bridging contact carriers 30, 31, 32, 33.

The plunger is mounted in a frictionless bearing manner for reciprocating relative to the frame by means com prising a pair of leaf springs 84, 85. Leaf spring 84 suspends the collar end of the plunger from the frame. Leaf spring 84 is connected to the collar portion of the plunger by screws 86 which extend through a. bar 88, the leaf spring 84 and a bar 89 and into the plunger. A dowel pin 87 connects the leaf spring and bars 88, 89. Leaf spring 84 is mounted on a projection 70 of the frame by screws 90 and a dowel pin 91 which extend through a bar 92 and the leaf spring into projection 70 of the frame.

Leaf spring 85 passes through an opening 105 in plate 86 to suspend the other end of the plunger from the frame. Leaf spring 85 is connected to the extension22 of the plunger by a coil spring 93 which is compressed between a bar 94 and a bracket 95. Bracket 95 is welded to plate 80 and receives one end of the coil spring in a recess 96 in the bracket. The other end of the coil spring engages a projection 97 on bar 94. The leaf spring 85 is connected betwen bar 94 and a bar 93 by means such as rivets 99. The extension 22 of the plunger has a projection 100 on the end thereof which passes through aligned holes in bar 98, leaf spring 85 and bar 94. Coil spring 93 thus forces the bar 98 against a shoulder portion 101 of the extension 22 for connecting the leaf spring 35 to the plunger. The coil spring 93 also provides resistance to the pull of the electromagnet on the plunger. Leaf spring 85 is mounted on plate 80 by screws 102 and a dowel pin 103 which extend through a bar 104 and into plate 80.

As shown in Fig. 2, the leaf springs 84, 85 are connected to the plunger at points on the axis thereof and are connected to the frame at points on a line parallel to the axis of the plunger and the springs are arranged to pivot at points on a line parallel to the axis of the plunger. The planes of the leaf springs are substantially parallel. The axis of the plunger, the leaf springs and the line between the pivott points of the springs define a parallelogram throughout the reciprocating motion of the plunger. The plunger, as thus suspended from the frame, reciprocates without friction and with no twisting torques being applied to the plunger.

Each of the bridging contact carriers 30, 31, 32, 33 is mounted on the plunger as shown in Figs. 1, 3 and for carrier 30. A lip portion 35 of the carrier 30 extends over the collar portion of the plunger and a screw 34 rigidly connects the carrier in a recess 36 in the collar portion 21 of the plunger. A shield portion 37 extends down alongside the frame and shields the frame from arcs drawn between the bridging contact 49 and the stationary contacts 50, 51. The carrier has a projecting portion 38 and a projecting portion 39 between which the bridging contact assembly is mounted. Since the frame and the plate are connected so as to move together as a unitary structure, the plunger, being mounted on this structure, also moves therewith as a unit when the neck portion 14 is moved inopening to position the.

frame on the panel. The carriers 30, 31, 32, 33, being rigidly mounted on the plunger, move through the slots 71, 72, 72, 74 in the frame as the plunger reciprocates. These slots and the plunger mounted carriers extending therethrough form splines which also insure that the plunger and carriers move as a unit with the frame when positioning the frame on the panel.

Each of the bridging contact assemblies is mounted on the carriers as shown in Figs. 3 and 5 for bridging con tact 40 and carrier 30. An iron core member 44 is rigidly connected to the projecting portion 39 of the carrier by a screw 45. The U-shaped bridging contact 40 is resiliently mounted on the carrier for movement relative thereto when the bridging contact engages the stationary contacts. A coil spring 46 engages a projection .46 on the projecting portion 38 of the carrier and fits into a recess 47 in an iron armature member 48 to rigidly mount armature 48 on bridging contact 40 and to retacts by positioning the frame on the panel.

siliently mount the bridging contact on the carrier. The core 44 and the armature 43 may be of any suitable shape to form an iron path substantially encircling the bridging contact, and are here both shown as U-shaped members.

Since the frame, the plate, the plunger and the carriers all move as a unitary structure when positioning the frame on the panel, the bridging contacts, being mounted on the carrier, may be aligned with the stationary con- This may be done by loosening screws 81, S2, 83, moving the frame in opening 15 to align the bridging contacts with the stationary contacts, and tightening these screws to secure the frame on the panel in the selected position with the contacts aligned.

When coil 11 is deenergized, the plunger is in the position shown. When the coil is energized, the plunger is attracted in the direction to compress spring 93 and to close the air gap. The bridging contacts are carried into engagement with the stationary contacts before the plunger has reached its limit of travel, and the bridging contact therefore compresses spring 46 as the plunger continues to travel after the contacts have engaged. The contacts thus firmly engage as spring 46 compresses and the bridging contact 40 and the armature 48 separate from core 454 on carrier 30. The current flowing through stationary contacts 50, 51 and bridging contact 40 produces electromagnetic forces tending to separate the bridging contact from the stationary contacts, and inasmuch as the bridging contact is resiliently mounted on the carrier, it is very likely to separate from the stationary contacts, especially during a high current period, such as a transient or a short circuit condition. The core 44 and armature 48, however, utilize the flux encircling the bridging contact to attract the armature 48 to the core 44. The armature, being fixed on the bridging contact, therefore forces the bridging contact toward the stationary contacts to prevent separation of the contacts. Because the core 44 and armature 48 are both on the bridging contact carrier away from the stationary contacts, they do not interfere with the arc blowout function of the magnets associated with the stationary contacts.

When the coil 11 is deenergized, the spring 93 forces the plunger back against stop bar 27 to the position shown. The reciprocating plunger, because of the frictionless bearing suspension provided by the leaf springs, moves freely through the frame without any undesirable twisting action.

Although only one embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the'invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A switch comprising a pair of stationary contacts, a contact carrier, a bridging'contact resiliently mounted on said carrier. to be movable relative thereto, means for moving said carrier to carry said bridging contact into and out of bridging engagement with said stationary contacts, an iron core rigidly mounted on said carrier, an iron armature rigidly mounted on said bridging contact, said core and armature together substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said core thereby forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow through said contacts.

2. A switch comprising -a pair of stationary contacts, a contact carrier, a bridging contact resiliently mounted on said carrier to be movable relative thereto, means for moving said carrier to carry said bridging contact into and out of bridging engagement with said stationary contacts, said contacts when engaged forming a U-shaped current path, an iron core rigidly mounted on said carrier, an iron armature rigidly mounted on said bridging contact, said core and armature together substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said core thereby forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow through said contacts. 7

3. A switch comprising a pair of stationary contacts, a contact carrier, a U-shaped bridging contact resiliently mounted on said carrier to be movable relative thereto in the direction of motion of said carrier, means for moving said carrier to carry said bridging contact into and out of bridging engagement with said stationary contacts, an iron core rigidly mounted on said carrier in a position thereon between said bridging contact and said stationary contacts, an iron armature rigidly mounted on said bridging contact, said core and armature together substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said core thereby forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow through said contacts.

4. A switch comprising a pair of stationary contacts, a contact carrier, a bridging contact resiliently mounted on said carrier to be movable relative thereto, means for moving said carrier to carry said bridging con-tact into and out of bridging engagement with said stationary contacts, said contacts when engaged forming a U-shaped current path, a permanent magnet located within each of said stationary contacts for extinguishing arcs drawn between said bridging contact and said stationary contacts, an iron core rigidly mounted on said carrier, an iron armature rigidly mounted on said bridging contact, said core and armature together substantialy encircling said bridging contact to'utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said core thereby forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow through said contacts.

5. A switch comprising a panel having a pair of stationary contacts mounted thereon, said panel having an opening therethrough, a frame having a shoulder portion abutting said panel on one side thereof about said opening and having a neck portion extending from said shoulder portion and projecting into said opening a distance not greater than the thickness of said panel, said neck being movable within said opening to position said frame on said panel, a plunger carried by said frame and mounted on said frame for reciprocating motion relative thereto, a bridging contact carried by said plunger for cooperation with said pair of stationary contacts, a plate extending overlappingly across said opening and abutting said panel on the opposite side thereof, releasable fastening means connecting said plate to said frame within said opening for releasably clamping said panel between said shoulder portion and said plate to permit moving said frame and plate together on said panel for selectively positioning said frame on said panel and to secure said frame to said panel in a selected position to thereby align said bridging contact with said stationary contacts.

6. A switch comprising a panel having a pair of stationary contacts mounted thereon, said panel having a circular opening therethrough, a frame having a shoulder portion abutting said panel on one side thereof about said opening and having a circular neck portion extending from said shoulder portion and projecting into said opening a distance less than the thickness of said panel, said neck being rotatable within said opening to rotatably position said frame on said panel, a plunger carried by said frame and mounted on said frame for reciprocating motion relative thereto, a bridging contact carried by said plunger for cooperation with said pair of stationary contacts, a plate extending overlappingly across said opening and abutting said panel on the opposite side thereof, releasable fastening means connecting said plate to said frame within said opening for releasably drawing said shoulder portion against said one side of said panel and the overlapping portions of said plate against the opposite side of said panel to permit rotating said frame and plate together on said panel for selectively positioning said frame on said panel and to secure said frame to said panel in a selected position to thereby align said bridging contact with said stationary contacts.

7. A switch comprising a panel having a pair of stationary contacts mounted thereon and having an opening therethrough, a frame, a movable plunger, a contact carrier mounted on said plunger to be moved therewith, a bridging contact resiliently mounted on said carrier to be movable relative thereto, bearing means comprising a pair of leaf springs mounted on said frame and extending therefrom in substantial parallelism and movably suspending said plunger between the extended ends of said leaf springs and supporting said bridging contact for reciprocating movement, actuating means for reciprocating said plunger on said hearing means to move said carrier and said bridging contact into and out of bridging egnagement with said stationary contacts, an iron core rigidly mounted on said carrier in a position thereon between said bridging contact and said stationary contacts, and an iron armature rigidly mounted on said bridging contact, said core and armature together substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said core forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow through said contacts, said frame having a shoulder portion abutting said panel on one side thereof about said opening and having a neck portion extending from said shoulder portion and projecting into said opening a distance not greater than the thickness of said panel, said neck being movable within said opening to position said frame on said panel, a plate extending overlappingly across said opening and abutting said panel on the opposite side thereof, and releasable fastening means connecting said plate to said frame within said opening for releasably clamping said panel between said shoulder portion and said plate to permit moving said frame and the plate together on said panel for selectively positioning said frame on said panel and to secure said frame to said panel in a selected position to thereby align said bridging contact with said stationary contacts.

8. A switch comprising a panel having a pair of stationary contacts mounted thereon and having an opening therethrough, a frame, a movable plunger, a contact carrier mounted on. said plunger to be moved therewith, a bridging contact resiliently mounted on said carrier to be movable relative thereto, bearing means comprising. a pair of leaf springs mounted on said frame and extending therefrom in substantial parallelism and movably suspending said plunger between the extended ends of said leaf springs and supporting said bridging contact for reciprocating movement, actuating. means for reciprocating said plunger on said bearing, means to move said carrier and said bridging contact in reciprocating movement into and out of .bridging engagement with said stationary contacts, an iron core rigidly mounted on said carrier in a position thereon between said. bridging contact and said stationary contacts, and an iron armature rigidly mounted on said bridging contact, said core and armature together substantially encircling said bridging contact and being disposed thereon in a position to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature in one of the reciprocating movement directions toward said core forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow through said contacts, said frame having a shoulder portion abutting said panel on one side thereof about said opening and having a neck portion extending from said shoulder portion and projecting into said opening a distance not greater t-hanthe thickness of said panel, said neck being movable within said opening to position said frame. on said panel, a plate extending overlappingly across said opening and abutting said panel on the opposite side thereof, and releasable fastening means connecting said plate to said frame within said opening for releasably clamping said panel between said shoulder portion and said plate to permit moving said frame and the plate together on said panel for selectively positioning said frame on said panel and to; secure said frame to said panel in a selected position to thereby align said bridging. contact with said stationary contacts for the specified reciprocating movement.

9. A switch comprising a pair of stationary contacts, a contact carrier, a bridging contact resiliently mounted on said carrier to be movable relative thereto, means for moving said carrier to carry said bridging contact into and out of bridging engagement with said stationary contacts, a ferromagnetic core rigidly mounted on said carrier, a ferromagnetic armature rigidly mounted on said bridging contact, said core and armature together substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows contact from said stationary contacts by theelectromag substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said corethereby forcing said bridging contact against said stationary contacts to prevent separation of said bridging contact from said stationary contacts by the electromagnetic forces produced by current flow in either direction through said contacts.

11. A switch comprising a pair of stationary contacts, a. contact carrier, a U-shaped bridging contact resiliently mounted on said carrier to be movable relative thereto in the direction of motion of said carrier, means for moving said carrier to carry said bridging contact into and out of bridging engagement with said stationary contacts, a ferromagnetic core rigidly mounted on said carrier in a position thereon between said bridging contact and said stationary contacts, a ferromagnetic armature rigidly mounted on said briding contact, said core and armature together substantially encircling said bridging contact to utilize the flux encircling said bridging contact when current flows therethrough for attracting said armature toward said core thereby forcing said bridging contact against said stationary contacts to prevent separation of saidbridging contact from said stationary contacts by the electromagnetic forces produced by current flow in. either direction through said contacts.

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